In the scientific study of streams and rivers, it is desirable to take accurate readings of the various hydrological characteristics of the stream, particularly with regard to water flow. Many devices have been constructed in the past which are able, through various means, to measure the flow velocity of a liquid. Among these devices are the current meter disclosed in U.S. Pat. No. 1,034,399 (Buck) which employs a chamber and tube system for measuring velocity, the current meter disclosed in U.S. Pat. No. 1,709,100 (Tice) which employs an upright cylindrical runner to measure current flow velocity, and a flow meter as disclosed in U.S. Pat. No. 3,164,020 (Grover et al.) which uses a bladed rotor in the determination of fluid flow.
Another way of measuring flow velocity known in the prior art is to use a wheel of small buckets or cups, such as those disclosed in U.S. Pat. No. 1,593,291 (Critchlow). The bucket wheel device can be mounted upon a shaft and rotates in response to flow, generating a signal proportional to the fluid velocity. This bucket wheel design is quite commonly observed in anemometers, such as disclosed in U.S. Pat. No. 3,541,855 (Frenzen et al.).
Previous versions of bucket wheels designed for use in flow meters have generally been fabricated of metal and are hand assembled. These metal versions are generally machined under close tolerances, soldered on a jig, and then plated. This process creates bucket wheels or cup assemblies having many small irregularities that cause the devices to scatter around a standard rating. Further, these versions respond to the vertical component of velocity in addition to the horizontal component, thus causing further inaccuracies in the readings. What is desired is a bucket wheel assembly which can take accurate measurements of flow, which is lightweight but durable, and which is responsive only to the horizontal component of flow velocity, and non-responsive to the vertical component. It is also desirable to have a bucket wheel assembly which is cheaper and more economical to use than the prior art metal versions.